1973 Rebuild

[Matthew Abate]

Ah right! Yoke washers. I completely forgot about those. Thanks for the reminder.

Okay, I’ll look at adjusting the placement of the manifold and header first. Maybe that will be enough to mean I don’t need to shave the intake manifold. People had warned me that all exhausts need tweaking, but I don’t want to mess with the headers any more than necessary.

It’s nice to hear that that rectangular protrusion is thick and could handle shaving. I was starting to go down the ITB FI mental rabbit hole.

Edited November 22, 2022 by Matthew Abate

[Zed Head]

15 hours ago, Matthew Abate said:

The bottoms of my N36 intake manifolds are hitting the headers. The red circles in the photograph below show where I have contact. I am considering filing them until they have enough clearance, but I’m not sure what is in that spot and how thick that material is. I

Are they hitting the tubes of the headers?  Headers can release a lot of heat.  Used to be fun to take a high speed run at night then open the hood and look at the glowing red metal.  Not a Datsun but all headers are about the same.  Heat management is a problem with carbs.  Can't remember how you're fueling your engine.

[Matthew Abate]

Yeah, the bottom of the N36 is hitting the tops of the header pipes. I wanted to stick with SUs for a stock look, but I am guessing this header is really meant to go with a set of triple Mikunis.

It’s not a huge interference. If there is enough material there I can probably make it clear, but I am worried about the heat and getting a heat shield to fit.

[Patcon]

I believe that square section is a coolant chamber. Lrobably about as thick as that dimple is deep

[Matthew Abate]

@Patcon Do you think it’s deep enough to shave it?

I emailed Steve at @Ztheraphy and he said it’s very thin there. He also thinks my headers is for a 280, which may or may not be possible. Spirit garage doesn’t distinguish between the two (just LHD or RHD), so it is probable that this header is just not meant to work with the original intake manifold.

[dutchzcarguy]

9 hours ago, Matthew Abate said:

I am worried about the heat and getting a heat shield to fit.

I would use some heat isolating tape wrapped around the exhaust manifold! 

If you have a dirty old inlet N36 i would file that one to look how deep the water or air cavity is..

NICE work!  I like that exhaust manifold but i hear they often ( the cheap ones?) leak between the manifold and head..  This one looks made of better material. nice fat contact plate..  Your doing well!

[Matthew Abate]

I think my options at this point are either abandoning the SU system in favor of a DCOE setup (Mikunis or ITBs), which is $$$, or making an aluminum spacer to fit between the intake manifold and the head that brings the manifold out away from the header, which would have an impact on performance.

[Zed Head]

A spacer would probably work but it would need to be designed to work with the yokes.  The intake and exhaust surfaces need to be at about the same level for the yokes to clamp properly.

[Matthew Abate]

Just now, Zed Head said:

A spacer would probably work but it would need to be designed to work with the yokes.  The intake and exhaust surfaces need to be at about the same level for the yokes to clamp properly.

Z Car Depot has stepped yoke washers, so I’m going to check those to see what kind of leeway they would provide. I could also grind a small amount off the tab on the bottom of the manifold to compensate.

Another question I have is could these spacers be thinner at the top to angle the manifold up slightly and create more clearance. I’m thinking 3 to five degrees.

[Patcon]

I suspect just looking at the picture of the manifold that the metal isn't very thick. It might be a little thicker in the corner area. I would think the internal face of the casting area is flush with the internal face of the core plug, but the core plug are is raised so it's probably only as thick as the difference. Another crazy idea would to be to resurface the intake manifold at a slight bevel. Leave the bottom thickness pretty much unchanged and remove a mm or so off the top edge. The "yokes" should still clamp properly that way but it would tip the manifold up some. Just eyeballing it, it should raise the manifold by 2:1. So a mm off the top of the flange raises the manifold by 2mm

[Zed Head]

16 hours ago, Patcon said:

I believe that square section is a coolant chamber.

It's been discussed before, but the coolant might actually be for heating, as I recall.  There's a thermostatic valve in the line.  Some people don't run coolant through them, they block them off, I think.  So, maybe major modification is possible.  On the other hand though, cooling would probably be good, because the header pipes are so close.

Angling the mounting surface is a good idea except the the carbs will then be angled also.  You'd have to bring them back in to line by angle the mount from the manifold to the carb.

Surprised actually, that they don't fit right.  I wonder if the guy would take them back and remake you a set.  They look custom built.  He might appreciate the feedback too.  If you're having problems other people are too.  SU's are common.  You'd be doing him a big favor by letting him know.  Be nice and you might get a good result.  Hopefully he didn't order a big batch from some offshore company.  Good luck.

Edited November 23, 2022 by Zed Head
+ d

[Zed Head]

Here's a link to the company.  Never heard of them before now.  Don't know how it works, there's no parts shown.  He looks more like a representative for other companies.

https://jessestreeter.com/